package 第五周;
import java.util.Scanner;

public class Circle {
    public static void main(String[] args) {
        double area;
        Scanner r=new Scanner(System.in);
        System.out.println("请输入圆的半径:");
        double radius=r.nextDouble();
        area=Math.PI*radius*radius;
        System.out.println("圆的面积是:"+area);
        }
}
